Rab’s heritage with down products can’t be knocked, and the Infinity 300 – while pricy – has this in its favour before it’s even left the starting blocks. On paper it’s joint warmest bag in our test with the Mountain Equipment Xero, pushing its comfort limit to a more useful -2 deg C with an extreme of -18. The shell fabric – in and out – is Pertex Quantum GL, which is silky and windproof (and a bit transparent!), while the fill is 850 power white goose down. Insulation baffles run the length of the sleeping bag, allowing warmth to travel and improving lofting (fluffing) of the down to an impressive degree. This system – developed by InsoTect – features vertical baffles and ‘flow gates’ to hold the down in place, and is also featured in the Marmot Plasma 30. In use, the Rab Infinity 300 is excellent: luxurious-feeling, fluffy and pretty warm, featuring a shoulder baffle to avoid draughts and a double-ended ¾ zip for top ’n’ tail venting. The bag comes with a cotton lofting sack and a basic stuffsack that you can’t compress – the cinch buckle of which broke on first use, annoyingly. This might seem like a minor gripe, but at this price it really should be perfect.

The Rab Infinity 300 is a luxurious sleeping bag, which will no doubt be many people’s favourite. Ideal for spring in the hills; minor quality issues and a high price are the only problems.

Review by Simon IngramFirst published in Trail magazine August 2013

Marmot Plasma 30 (2013)

sleeping bags

spring/autumn

down

644g

£400

The Marmot Plasma 30 has a very hefty price tag, but this is nevertheless an outstanding sleeping bag that pulls off something rare: it actually seems better than Marmot says it is. In comparison to the Rab Infinity 300 – with which it shares a similar InsoTect insulation system and Pertex outer – it manages a higher fill power of goose down, includes little touches like popper closures on the neck baffle and zip ties, yet manages to weigh less than its rival. This is impressive in itself, but the surprises don’t stop there. The Marmot Plasma 30 feels a lot warmer than it suggests; the quoted comfort limit figure is -1 deg C (the Rab’s is -2 deg C) but the Marmot bag feels instantly warmer when used side by side with the Infinity. This could be due to the higher fill power or simply a better fit due to my body shape, but the high loft of the bag and the snugger fit overall means I personally would select this one for a slightly colder night out. Either way, there really isn’t much in it – and while this is arguably the better bag, for this reason that price is a big turn-off.